ITR V - Acknowledgement

Hello,

I have e filed my IT Return for AY 2011-12 and sent ITR V by speed post in the last week of July.

On the efiling website, the ITR V Receipt Status shows up as "ITR-V has been received in CPC."

However, I have still not received the "ITR-V Acknowledgement". How long does it take for this to arrive and does it arrive by post or by email?

Thanks a lot.

Gautam